Changes of Electrical Conductivity, Magnetic Susceptibility, and IR Spectra in the Ternary System Mon-xWxO3n-1

The temperature dependence of electrical resistivity, magnetic susceptibility as well as the diffuse reflectance spectra and IR-spectra from the visible to the infrared spectral region are measured. A transition from a quasi one-dimensional to a two-dimensional electrical conductivity for Mo8O23 and Mo9O26 is established and an increase of new bands in the IR-spectra indicates the phase transition due to the appearance of charge density waves in these temperature regions. The polycrystalline samples exhibit a high electrical resistivity at low temperatures which is caused by crystal defects and grain boundaries. The compounds with a high tungsten content exhibit a magnetic susceptibility with negative values, but a paramagnetic behaviour at low temperatures.